By Dr Mark Tyndall
Principal EMC Engineer
Consultancy & Research Department
York EMC Services
www.yorkemc.co.uk
This summer, I travelled on a railway which had no
need for my services. Le p'tit Train de Saint-Trojan is
a single-track, narrow-gauge, tourist line with three
stations and big, painted wooden tokens for the
drivers of the two diesel-engined locos to hand over
as they shuttle back and forth all day. Most railways,
however, are sufficiently complex that ignoring EMC
is not a risk that can be taken by their operators.
special concern for railways ever since electrification.
Running traction power for mile after mile down
narrow corridors, in parallel with signalling and
telecommunications cables, breaks one of the
cardinal rules of EMC. This has been recognised for
decades; BR 13422 was published in 1979.
Fast-forward to 1989 and the first EMC directive was
focussed solely on apparatus.
The UK's EMC
Regulations
referred
to
“excluded
installations” (installations were excluded from the CE
-marking requirements for apparatus), but it was left
to non-binding guidance to flesh out what an
installation operator needed to do to assure EMC.
Not until the current Directive, 2004/108/EC, did the
term Fixed Installation make an appearance, with its
statutory, harmonised requirements.
The EMC requirements for Fixed Installations,
including railways, stations and depots are regulated
by the current EMC Directive (2004/108/EC), and its
successor (2014/30/EU).
Network Rail standards set out the approach for
effective management of EMC and the
documentation of compliance; most other railways in
the UK (for example, London Underground) have
similar, explicit requirements. Rather than any one
set of specific requirements, this article considers the
overall philosophy of railway EMC management,
which we've successfully applied to projects
worldwide.
Electromagnetic compatibility, the ability for all the
systems in a particular environment to successfully
operate within defined parameters, has been a
A railway is a complex set of interdependent systems
with widely disparate requirements; they are
shoehorned into long, narrow strips of land and
expected to work together safely, reliably and
effectively. A mainline loco might draw 200A from
the overhead and simultaneously induce tens of volts
into line-side cabling connected to safety-critical
signalling
assets
or
carrying
low-level
telecommunications.
DC electrification, while
protected from the gross effects of AC induction,
brings its own issues, mainly surrounding stray
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current (but the rectification process often causes
ripple currents at 600 or 1200Hz, which can severely
perturb baseband audio signals for PA or station's
remote help systems).
Without proactive
management of compatibility, issues are simply being
saved up for the flurry of activity that marks the
commissioning phase.
before, or (in extreme cases) after, commissioning. At
this point, the phrases you hope not to hear from your
emergency EMC consultant are similar to those from an
emergency plumber: “who put that there?”, “well, I
wouldn't have done it like that”, and “it's no good, it'll
all have to come out”.
The EMC directive requires that a Fixed Installation be
suitably (non-) emissive for its environment, suitably
immune for its purpose, that it is installed using good
engineering practices and respecting the information on
the intended use of its components, and that the good
engineering practices are documented, with the
documentation held at the disposal of the relevant
national authorities for inspection for as long as the
installation is in operation. By the way, don't be fooled
by the reshuffle in the new directive; in 2014/30/EU, the
documentation requirements for installations have
The latest Network Rail philosophy for managing EMC
prefers explicit input from the early stages (GRIP 2 or 3),
while there is still a level of fluidity about how the
project will be successfully achieved.
The EMC
consultant will be involved with setting and assessing
EMC hazards in the risk register. An EMC strategy can
set overall goals, constraints and direction at this stage.
simply been moved (from Annex I to Article 19), and are
as binding as the documentation requirements for
apparatus.
However, the documentation requirements are not
comprehensively set out, and differing interpretations
from various stakeholders, and differing on-the-ground
requirements for each particular project mean that
there isn't a simple, template that can be used to
extrude uniform EMC documentation for each project.
Unfortunately, this occasionally means that EMC is
ignored, postponed or forgotten until a few weeks
At GRIP 4, a multi-disciplinary hazard identification
workshop will re-evaluate the EMC hazards on the risk
register, and an EMC management plan can specify
appropriate standards for both procurement and
design, and controls to manage third-party and legacy
assets. At this stage, the EMC consultant can provide
targeted, specific advice which can still be heeded
before the design is finalised. EMC procurement
specifications can also be set before off-the-shelf
components are chosen, or contracts with subcontractors are signed: technical and documentation
requirements for suppliers can be more easily made a
contractual matter.
GRIP 5 should see any design risks closed out, possibly
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with cable studies to model induced voltages. Ideally,
procurement review should occur as systems and
suppliers are chosen – with the most complex subsystems undergoing a microcosm of this EMC
management. However, this may be more difficult in
situations where there is an abrupt hand-over from
GRIP 5 designer to GRIP 6 contractor.
On-site EMC measurements, that most conspicuous of
EMC activities, may be required. This depends on
whether there are specific risks in the register which are
most effectively closed via such measurements. As well
as measurements to EN 50121, measurements of
induced longitudinal and transverse (including
psophometric) voltages may be required on line-side
cables. On DC railways, measurements of stray currents
Why not consider attending our EMC in Railways
training course. This 5 day course is designed to deliver
an in-depth study of EMC in the complex railway
environment. It provides an understanding of the
importance of managing EMC from project concept to
completion.
The legal EMC requirements will be explained and how
these are satisfied by use of standards and the
Technical Documentation.
The course includes general EMC background topics
such as EM waves and radiation, decibels, the EMC
Directive and commercial standards. Railway specific
topics include an introduction to railway EMC standards,
overview of signalling, threats and AC and DC traction.
The course also covers technical documentation,
interoperability and EMC management throughout the
project.
The New Legislative Framework (NLF), and the new EMC
Directive 2014/30/EU which comes into force on 20th
April 2016, are also presented, bringing you fully up to
date with current and future requirements.
For more information please visit our website
www.yorkemc.co.uk.
may be required. The commissioning phase can be
fraught; having the EMC testing requirements specified,
agreed, booked and confirmed well in advance pays
dividends all round.
The final stage of EMC documentation ensures that no
issues remain open, but also summarises the activities
and the documentation; this helps any EMC lessons to
surface, which in turn helps ensure the safety, reliability
and effectiveness of the railway.
Dr Mark Tyndall is a Principal EMC Engineer in the
Consultancy and Research Department at York
EMC Services.
For more information please contact us:
E-mail; enquiry@yorkemc.co.uk
Tel;+44 (0) 1904 324440
Fax; +44 (0) 1904 324434
www.yorkemc.co.uk
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